A full moon in October is known as a "Hunters Moon". Credit: David Haworth/stargazing.net
If you live in the northern hemisphere, than stargazing during the early autumn months can a bit tricky. During certain times in these seasons, the stars, planets and Milky Way will be obscured by the presence of some very beautiful full moons. But if you’re a fan of moongazing, then you’re in luck.
Because it is also around this time (the month of October) that people looking to the night sky will have the chance to see what is known as a Hunter’s Moon. A slight variation on a full moon, the Hunter’s Moon has long been regarded as a significant event in traditional folklore, and a subject of interest for astronomers.
Definition:
Also known as a sanguine or “blood” moon, the term “Hunters Moon” is used traditionally to refer to a full moon that appears during the month of October. It is preceded by the appearance of a “Harvest Moon”, which is the full moon closest to the autumnal equinox (which falls on the 22nd or 23rd of September).
The Hunter’s Moon typically appears in October, except once every four years when it doesn’t appear until November. The name dates back to the First Nations of North America. It is so-called because it was during the month of October, when the deers had fatted themselves over the course of the summer, that hunters tracked and killed prey by autumn moonlight, stockpiling food for the coming winter.
Full Moon Rising Over Northwest Georgia on June 22nd, 2013. Credit and copyright: Stephen Rahn.
Characteristics:
Although typically the Moon rises 50 minutes later each day, things are different for the Hunter’s Moon (as well as the Harvest Moon). Both of these moons usually rise 30 minutes later on each successive night, which means that sunset and moonrise are not far apart.
This means there is prolonged periods of light during this time of the the year, which is the reason why these moons have traditionally been used by hunters and farmers to finish their work.
This difference between the timing of the sunset and moonrise is due to its orbit, meaning that the angle the Moon makes with the horizon is narrower during this time of year. The Hunter’s Moon is generally not bigger or brighter than any of the other full moons. Thus, the only difference between it and other full moons is the that the time between sunset and moonrise is shorter.
History of Observation:
Because the approach of winter signaled the possibility of going hungry in pre-Industrial times, the Hunter’s Moon was generally accorded with special honor, historically serving as an important feast day in both northern Europe and among many Native American tribes.
Traditionally, Native American hunters used the full moon of October to stalk deer and to spot foxes at night as they prepared for the coming winter. Because the fields were traditionally reaped in late September or early October, hunters could easily see foxes and other animals that came out to glean from the fallen grains.
The Hunter’s Moon is accorded similar significance in Europe, where it was also seen as a prime time to hunt during the post-harvest, pre-winter period when conditions were optimal for spotting prey. However, the term did not enter into usage for Europeans until after they made contact with Indigenous Americans and began colonizing North America.
The first recorded mentions of a “Hunter’s Moon” began in the early 18th century. The entry in the Oxford English Dictionary for “Hunter’s Moon” cites a 1710 edition of The British Apollo, where the term is attributed to “the country people”. The names are now referred to regularly by American sources, where they are often popularly attributed to “the Native Americans”.
In India, the harvest festival of Sharad Purnima, which marks the end of the monsoon season, is celebrated on the full moon day of the lunar month of Ashvin (September-October). There is a traditional celebration of the moon during this time that is known as the “Kaumudi” celebration – which translated, means “moonlight”.
The harvest festival of Shrad Purnima is celebrated on the full moon day of the Hindu lunar month of Ashvin. Credit: dfwhindutemple.org
Interesting Facts:
Sometimes, the Harvest Moon is mistaken for the Hunter’s Moon because once every four years or so the Harvest Moon is in October instead of September. When that happens, the Hunter’s Moon is in November. Traditionally, each month’s full moon has been given a name, although these names differ according to the source.
Other full moons of interest include the Wolf Moon in January, the Strawberry Moon in June, the Sturgeon Moon in August, the Cold Moon in December, and the Pink Moon in April. All of the full moons have different characteristics due to the location of the ecliptic – i.e. the path of the Sun – at the time of each.
The Hunter’s Moon is also associated with feasting. In the Northern Hemisphere, some Native American tribes and some places in Western Europe held a feast day. This feast day, the Feast of the Hunter’s Moon, was not been held since the 1700’s. However, the Feast of the Hunters’ Moon is a yearly festival in Lafayette, Indiana, which has been held in late September or early October every year since 1968.
We have many interesting articles about the moon here at Universe Today. For example, here are some about the red moon and a rundown of what a full moon is all about.
Various meteorites from 2008 TC3.
Credit: P. Jenniskens, et. al. Click image for full description
Asteroids, meteors, and meteorites … It might be fair to say these rocks from space inspire both wonder and fear among us Earthlings. But knowing a bit more about each of them and how they differ may eliminate some potential misgivings. While all these rocks originate from space, they have different names depending their location — i.e. whether they are hurtling through space or hurtling through the atmosphere and impacting Earth’s surface.
In simplest terms here are the definitions:
Asteroid: a large rocky body in space, in orbit around the Sun.
Meteoroid: much smaller rocks or particles in orbit around the Sun.
Meteor: If a meteoroid enters the Earth’s atmosphere and vaporizes, it becomes a meteor, which is often called a shooting star.
Meteorite: If a small asteroid or large meteoroid survives its fiery passage through the Earth’s atmosphere and lands on Earth’s surface, it is then called a meteorite.
Another related term is bolide, which is a very bright meteor that often explodes in the atmosphere. This can also be called a fireball.
Let’s look at each in more detail:
Asteroids An artists impression of an asteroid belt. Credit: NASA
Asteroids are found mainly in the asteroid belt, between Mars and Jupiter. Sometimes their orbits get perturbed or altered and some asteroids end up coming closer to the Sun, and therefore closer to Earth. In addition to the asteroid belt, however, there have been recent discussions among astronomers about the potential existence of large number asteroids in the Kuiper Belt and Oort Cloud. You can read a paper about this concept here, and a good article discussing the topic here.
The asteroid Vesta as seen by the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA
Asteroids are sometimes referred to as minor planets or planetoids, but in general, they are rocky bodies that do not have an atmosphere. However, a few have their own moons. Our Solar System contains millions of asteroids, many of which are thought to be the shattered remnants of planetesimals – bodies within the young Sun’s solar nebula that never grew large enough to become planets.
The size of what classifies as an asteroid is not extremely well defined, as an asteroid can range from a few meters wide – like a boulder — to objects that are hundreds of kilometers in diameter. The largest asteroid is asteroid Ceres at about 952 km (592 miles) in diameter, and Ceres is so large that it is also categorized as a dwarf planet.
Most asteroids are made of rock, but as we explore and learn more about them we know that some are composed of metal, mostly nickel and iron. According to NASA, a small portion of the asteroid population may be burned-out comets whose ices have evaporated away and been blown off into space. Recently, astronomers have discovered some asteroids that mimic comets in that gas and dust are emanating from them, and as we mentioned earlier, there appears to be a large number of bodies with asteroid-like compositions but comet-like orbits.
How Often Do Asteroids Hit Earth?
Meteor Crater near Winslow, Arizona. Image credit: NASA.
While we know that some asteroids pass very close to Earth’s orbit around the Sun, we’ve been lucky in the history of humanity that we haven’t had a large asteroid hit Earth in the past several thousand years. It wasn’t until satellite imagery of Earth became widely available that scientists were able to see evidence of past asteroid impacts.
One of the more famous impact craters on Earth is Meteor Crater in Arizona in the US, which was made by an impact about 50,000 years ago. But there are about 175 known impact around the world – a few are quite large, like Vredefort Crater in South Africa which has an estimated radius of 190 kilometers (118 miles), making it the world’s largest known impact structure on Earth. Another notable impact site is off the coast of the Yucatan Peninsula in Mexico, and is believed to be a record of the event that led to the extinction of the dinosaurs 65 million years ago. You can see images of some of the most impressive Earth impact craters here.
These days, asteroid impacts are less of a threat. NASA estimates that about once a year an automobile-sized asteroid enters Earth’s atmosphere, creates an impressive fireball and disintegrates before ever reaching the surface. Studies of Earth’s history indicate that about once every 5,000 years or so on average an object the size of a football field hits Earth and causes significant damage. Once every few million years on average an object large enough to cause regional or global disaster impacts Earth. You can find more information about the frequency of impacts in this article from NASA.
Meteors, Meteoroids and Bolides
A bright meteor from September 21, 1994. Credit: John Chumack.
Space debris smaller than an asteroid are called meteoroids. A meteoroid is a piece of interplanetary matter that is smaller than an asteroid and frequently are only millimeters in size. Most meteoroids that enter the Earth’s atmosphere are so small that they vaporize completely and never reach the planet’s surface. When they burn up during their descent, they create a beautiful trail of light known as a meteor, sometimes called a shooting star.
Mostly these are harmless, but larger meteors that explode in the atmosphere – sometimes called bolides — can create shockwaves, which can cause problems. In February 2013 a meteor that exploded over Chelyabinsk, Russia shattered windows with its air blast. This meteoroid or bolide was estimated to be 18 meters (59 feet) in diameter. In 1908, a rocky meteoroid less than 100 meters in diameter is believed to have entered the atmosphere over the Tunguska region of Siberia in 1908 and the resulting shockwave knocked down trees for hundreds of square kilometers
How often is Earth hit by meteroids?
Chelyabinsk fireball recorded by a dashcam from Kamensk-Uralsky north of Chelyabinsk where it was still dawn.
Because of the Chelyabinsk meteor in 2013, astronomers have acquired more information about the frequency of larger meteors that hit Earth, and there is now a growing consensus that the Earth gets hit by bigger space rocks more often than we previously thought. You can read more about that concept here.
This video from the B612 Foundation shows a visualization of the location of 26 space rocks that hit Earth between 2000 and 2013, each releasing energy equivalent to some of our most powerful nuclear weapons. The B612 foundation says that a Hiroshima-scale asteroid explosion happens in our atmosphere on average once a year, but many are not detected because they explode high in the atmosphere, or because most of the Earth’s surface is water and even a large percentage of land is fairly uninhabited by humans.
Estimates vary of how much cosmic dust and meteors enter Earth’s atmosphere each day, but range anywhere from 5 to 300 metric tons. Satellite observations suggest that 100-300 metric tons of cosmic dust enter the atmosphere each day. This figure comes from the rate of accumulation in polar ice cores and deep-sea sediments of rare elements linked to cosmic dust, such as iridium and osmium.
But other measurements – which includes meteor radar observations, laser observations and measurements by high altitude aircraft — indicate that the input could be as low as 5 metric ton per day. Read more about this here.
For a documented list of bolide events, you can check out this page from JPL.
Meteorite A stunning slice of the Glorieta pallasite meteorite cut thin enough to allow light to shine through its many olivine crystals. Credit: Mike Miller
If any part of a meteoroid survives the fall through the atmosphere and lands on Earth, it is called a meteorite. Although the vast majority of meteorites are very small, their size can range from about a fraction of a gram (the size of a pebble) to 100 kilograms (220 lbs) or more (the size of a huge, life-destroying boulder). Meteorites smaller than 2mm are classified as micrometeorites.
Meteorites have traditionally been divided into three broad categories, depending on their structure, chemical and isotopic composition and mineralogy. Stony meteorites are rocks, mainly composed of silicate minerals; iron meteorites that are largely composed of metallic iron-nickel; and, stony-iron meteorites that contain large amounts of both metallic and rocky material.
Meteorites have also been found on the Moon and Mars and conversely, scientists have traced the origination of the meteorites found here on Earth to four other bodies: the Moon, Mars, the asteroid 4 Vesta, and the comet Wild 2. Meteorites are the source of a great deal of the knowledge that we have have about the composition of other celestial bodies.
How Often Do Meteorites Hit Earth?
On Feb. 28, 2009, Peter Jenniskens (SETI/NASA), finds his first 2008TC3 meteorite after an 18-mile long journey. “It was an incredible feeling,” Jenniskens said. The African Nubian Desert meteorite of Oct 7, 2008 was the first asteroid whose impact with Earth was predicted while still in space approaching Earth. 2008TC3 and Chelyabinsk are part of the released data set. (Credit: NASA/SETI/P.Jenniskens)
According to the Planetary Science Institute, it is estimated that probably 500 meteorites reach the surface of the Earth each year, but less than 10 are recovered. This is because most fall into water (oceans, seas or lakes) or land in remote areas of the Earth that are not accessible, or are just not seen to fall.
In short, the difference between asteroids and meteors all comes down to a question of location. Asteroids are always found in space. Once it enters an atmosphere, it becomes a meteor, and then a meteorite after it hits the ground. Each are made of the same basic materials – minerals and rock – and each originated in space. The main difference is where they are when they are being observed.
A multi-ringed, oval shaped corona around the Sun on May 30, 2015 seen from northern Minnesota. The white spots are aspen seeds better known as "cotton fluff". Credit: Bob King
Don’t be surprised if you look up in the Sun’s direction and squint with itchy, watery eyes. You might be staring into billows of tree pollen wafting through your town. It’s certainly been happening where I live.
When conditions are right, billions of microscopic pollen grains consort to create small, oval-shaped rings around a bright Moon during the peak of the spring and early summer allergy season. With the Full Moon coming up this week, there’s no better time to watch for them.
Pollen grains from a variety of different common plants including sunflower, morning glory, prairie hollyhock and evening primrose magnified 500x and colorized. The green, bean-shaped grain at lower left is 0.05 mm across. Credit: Dartmouth Electron Microscope Facility
Because they’re often lost in the glare of the Sun or Moon, the key to finding one is to hide the solar or lunar disk behind a thick tree branch, roof or my favorite, the power pole. Look for a telltale oval glow, sometimes tinted with rainbow colors, right up next to the Moon or Sun’s edge. Common halos, those that form when light is refracted by ice crystals, span 44° compared to pollen coronas, which measure just a few degrees in diameter.
To see or photograph coronas, you need plenty of light. The Sun’s ideal, but so is the Moon around full. Fortunately, that happens on June 2, neatly fitting into the sneezing season. Last night, the same grains — most likely pine tree pollen — also stoked a lunar corona. Once my eyes were dark adapted and the Moon hidden by an arboreal occulting instrument (tree branch), it was easy to see.
A lunar pollen corona on May 30, 2015. The Moon was hidden by a utility pole. Like the solar version, this one was also oval and measured about 3.5° across. The shape is caused by elongated pollen grains fact that orient themselves as they drift in the wind. Credit: Bob King
One of things you’ll notice right away about these biological bullseyes is that they’re not circular. Pollen coronas are oval because the pollen particles are elongated rather than spherical like water droplets. When light from the moon or sun strikes pollen, the minute grains diffract the light into a series of closely-spaced colored rings. I’ve read that pine and birch produce the best coronas, but spruce, alder and and others will work, too.
And here’s another amazing thing about these coronas. You don’t need a transparent medium to produce them. No ice, no water. All that’s necessary are very small, similarly-shaped objects. Light waves are scattered directly off their surfaces; the waves interfere with one another to create a diffraction pattern of colored rings.
A lunar pollen corona photographed on June 22, 2008 displays “bumps” or extensions at approximately 90° angles around its periphery. Credit: Bob King
Pollen coronas tend to become more elongated when the Sun or Moon is closer to the horizon, so look be on the lookout during those times for more extreme shapes. For some reason I’ve yet to discover, pollen disks sometimes exhibit “bumps” or extensions at their tops, bottoms and sides.
So many of us suffer from allergies, perhaps the glowing presence of what’s causing all the inflammation will serve as partial compensation for our misery.
Artist's illustration of a SpaceX Starship lands on Mars. Credit: SpaceX
Welcome back to our series on Settling the Solar System! Today, we take a look at that cold and dry world known as “Earth’s Twin”. I’m talking about Mars. Enjoy!
Mars. It’s a pretty unforgiving place. On this dry, desiccated world, the average surface temperature is -55 °C (-67 °F). And at the poles, temperatures can reach as low as -153 °C (243 °F). Much of that has to do with its thin atmosphere, which is too thin to retain heat (not to mention breathe). So why then is the idea of colonizing Mars so intriguing to us?
Well, there are a number of reasons, which include the similarities between our two planets, the availability of water, the prospects for generating food, oxygen, and building materials on-site. And there are even long-term benefits to using Mars as a source of raw materials and terraforming it into a liveable environment. Let’s go over them one by one…
Examples in Fiction:
The idea of exploring and settling Mars has been explored in fiction for over a century. Most of the earliest depiction of Mars in fiction involved a planet with canals, vegetation, and indigenous life – owing to the observations of the astronomers like Giovanni Schiaparelli and Percival Lowell.
However, by the latter half of the 20th century (thanks in large part to the Mariner 4 missions and scientists learning of the true conditions on Mars) fictional accounts moved away from the idea of a Martian civilization and began to deal with humans eventually colonizing and transforming the environment to suit their needs.
Artist impression of a Mars settlement with cutaway view. Credit: NASA Ames Research Center
This shift is perhaps best illustrated by Ray Bradbury’s The Martian Chronicles(published in 1950). A series of short stories that take place predominantly on Mars, the collection begins with stories about a Martian civilization that begins to encounter human explorers. The stories then transition to ones that deal with human settlements on the planet, the genocide of the Martians, and Earth eventually experiencing nuclear war.
During the 1950s, many classic science fiction authors wrote about colonizing Mars. These included Arthur C. Clarke and his 1951 story The Sands of Mars, which is told from the point of view of a human reporter who travels to Mars to write about human colonists. While attempting to make a life for themselves on a desert planet, they discover that Mars has native life forms.
In 1952, Isaac Asimov released The Martian Way, a story that deals with the conflict between Earth and Mars colonists. The latter manage to survive by salvaging space junk and are forced to travel to Saturn to harvest ice when Earth enforces an embargo on their planet.
Robert A. Heinlein’s seminal novel Stranger in a Strange Land (1961) tells the story of a human who was raised on Mars by the native Martians and then travels to Earth as a young adult. His contact with humans proves to have a profound effect on Earth’s culture, and calls into questions many of the social mores and accepted norms of Heinlein’s time.
Artist’s concept of possible exploration of the surface of Mars. Credit: NASA Ames Research Center
Philip K. Dick’s fiction also features Mars often, in every case being a dry, empty land with no native inhabitants. In his works Martian Time Slip (1964), and The Three Stigmata of Palmer Eldritch (1965), life on Mars is presented as difficult, consisting of isolated communities who do not want to live there.
In Do Androids Dream of Electric Sheep? (1968), most of humanity has left Earth after a nuclear war and now live in “the colonies” on Mars. Androids (Replicants) escaping illegally to come back to Earth claim that they have left because “nobody should have to live there. It wasn’t conceived for habitation, at least not within the last billion years. It’s so old. You feel it in the stones, the terrible old age”.
Kim Stanley Robinson’s Mars trilogy (published between 1992–1996), Mars is colonized and then terraformed over the course of many centuries. Ben Bova’s Grand Tour series – which deals with the colonization of the Solar System – also includes a novel titled Mars(1992). In this novel, explorers travel to Mars – locations including Mt. Olympus and Valles Marineris – to determine is Mars is worth colonizing.
Alastair Reynolds’ short story “The Great Wall of Mars” (2000) takes place in a future where the most technologically advanced humans are based on Mars and embroiled in an interplanetary war with a faction that takes issue with their experiments in human neurology.
Artist’s impression of the terraforming of Mars, from its current state to a livable world. Credit: Daein Ballard
In Hannu Rajaniemi’s The Quantum Thief (2010), we get a glimpse of Mars in the far future. The story centers on the city of Oubliette, which moves across the face of the planet. Andry Weir’s The Martian (2011) takes place in the near future, where an astronaut is stranded on Mars and forced to survive until a rescue party arrives.
Kim Stanley Robinson’s 2312(2012) takes place in a future where humanity has colonized much of the Solar System. Mars is mentioned in the course of the story as a world that has been settled and terraformed (which involved lasers cutting canals similar to what Schiaparelli described) and now has oceans covering much of its surface.
Proposed Methods:
NASA’s proposed manned mission to Mars – which is slated to take place during the 2030s using the Orion Multi-Purpose Crew Vehicle (MPCV) and the Space Launch System (SLS) – is not the only proposal to send humans to the Red Planet. In addition to other federal space agencies, there are also plans by private corporations and non-profits, some of which are far more ambitious than mere exploration.
The European Space Agency (ESA) has long-term plans to send humans, though they have yet to build a manned spacecraft. Roscosmos, the Russian Federal Space Agency, is also planning a manned Mars mission, with simulations (called Mars-500) having been completed in Russia back in 2011. The ESA is currently participating in these simulations as well.
In 2012, a group of Dutch entrepreneurs revealed plans for a crowdfunded campaign to establish a human Mars base, beginning in 2023. Known as Mars One, the plan calls for a series of one-way missions to establish a permanent and expanding colony on Mars, which would be financed with the help of media participation.
Mars-manned-mission vehicle (NASA Human Exploration of Mars Design Reference Architecture 5.0) Feb 2009. Credit: NASA
Other details of the MarsOne plan include sending a telecom orbiter by 2018, a rover in 2020, and the base components and its settlers by 2023. The base would be powered by 3,000 square meters of solar panels, and the SpaceX Falcon 9 Heavy rocket would be used to launch the hardware. The first crew of 4 astronauts would land on Mars in 2025; then, every two years, a new crew of 4 astronauts would arrive.
On December 2nd, 2014, NASA’s Advanced Human Exploration Systems and Operations Mission Director Jason Crusan and Deputy Associate Administrator for Programs James Reuther announced tentative support for the Boeing “Affordable Mars Mission Design.” Currently planned for the 2030s, the mission profile includes plans for radiation shielding, centrifugal artificial gravity, in-transit consumable resupply, and a return-lander.
SpaceX and Tesla CEO Elon Musk also announced plans to establish a colony on Mars with a population of 80,000 people. Intrinsic to this plan is the development of the Mars Colonial Transporter (MCT), a spaceflight system that would rely on reusable rocket engines, launch vehicles, and space capsules to transport humans to Mars and return to Earth.
As of 2014, SpaceX has begun developing the large Raptor rocket engine for the Mars Colonial Transporter, and a successful test was announced in September of 2016. In January 2015, Musk said that he hoped to release details of the “completely new architecture” for the Mars transport system in late 2015.
In June 2016, Musk stated in the first unmanned flight of the Mars transport spacecraft would take place in 2022, followed by the first manned MCT Mars flight departing in 2024. In September 2016, during the 2016 International Astronautical Congress, Musk revealed further details of his plan, which included the design for an Interplanetary Transport System (ITS) and estimated costs.
There may come a day when, after generations of terraforming and numerous waves of colonists, that Mars will begin to have a viable economy as well. This could take the form of mineral deposits being discovered and then sent back to Earth for sale. Launching precious metals, like platinum, off the surface of Mars would be relatively inexpensive thanks to its lower gravity.
But according to Musk, the most likely scenario (at least for the foreseeable future) would involve an economy based on real estate. With human populations exploding all over Earth, a new destination that offers plenty of room to expand is going to look like a good investment.
And once transportation issues are worked out, savvy investors are likely to start buying up land. Plus, there is likely to be a market for scientific research on Mars for centuries to come. Who knows what we might find once planetary surveys really start to open up!
Over time, many or all of the difficulties in living on Mars could be overcome through the application of geoengineering (aka. terraforming). Using organisms like cyanobacteria and phytoplankton, colonists could gradually convert much of the CO² in the atmosphere into breathable oxygen.
In addition, it is estimated that there is a significant amount of carbon dioxide (CO²) in the form of dry ice at the Martian south pole, not to mention absorbed by in the planet’s regolith (soil). If the temperature of the planet were raised, this ice would sublimate into gas and increase atmospheric pressure. Although it would still not be breathable by humans, it would be sufficient enough to eliminate the need for pressure suits.
A possible way of doing this is by deliberately triggering a greenhouse effect on the planet. This could be done by importing ammonia ice from the atmospheres of other planets in our Solar System. Because ammonia (NH³) is mostly nitrogen by weight, it could also supply the buffer gas needed for a breathable atmosphere – much as it does here on Earth.
Similarly, it would be possible to trigger a greenhouse effect by importing hydrocarbons like methane – which is common in Titan’s atmosphere and on its surface. This methane could be vented into the atmosphere where it would act to compound the greenhouse effect.
Zubrin and Chris McKay, an astrobiologist with NASA’s Ames Research center, have also suggested creating facilities on the surface that could pump greenhouse gases into the atmosphere, thus triggering global warming (much as they do here on Earth).
Other possibilities exist as well, ranging from orbital mirrors that would heat the surface to deliberately impacting the surface with comets. But regardless of the method, possibilities exist for transforming Mars’ environment that could make it more suitable for humans in the long run – many of which we are currently doing right here on Earth (with less positive results).
Another proposed solution is building habitats underground. By building a series of tunnels that connect between subterranean habitats, settlers could forgo the need for oxygen tanks and pressure suits when they are away from home.
Additionally, it would provide protection against radiation exposure. Based on data obtained by the Mars Reconnaissance Orbiter, it is also speculated that habitable environments exist underground, making it an even more attractive option.
Potential Benefits:
As already mentioned, there are many interesting similarities between Earth and Mars that make it a viable option for colonization. For starters, Mars and Earth have very similar lengths of days. A Martian day is 24 hours and 39 minutes, which means that plants and animals – not to mention human colonists – would find that familiar.
Diagram showing the habitable zones of the Solar System (upper row) and the Gliese 581 system (lower row). Based on a diagram by Franck Selsis, Univ. of Bordeaux. Credit: ESO
Mars also has an axial tilt that is very similar to Earth’s, which means it has the same basic seasonal patterns as our planet (albeit for longer periods of time). Basically, when one hemisphere is pointed towards the Sun, it experiences summer while the other experiences winter – complete with warmer temperatures and longer days.
This too would work well when it comes to growing seasons and would provide colonists with a comforting sense of familiarity and a way of measuring out the year. Much like farmers here on Earth, native Martians would experience a “growing season”, a “harvest”, and would be able to hold annual festivities to mark the changing of the seasons.
Also, much like Earth, Mars exists within our Sun’s habitable zone (aka. “Goldilocks zone“), though it is slightly towards its outer edge. Venus is similarly located within this zone, but its location on the inner edge (combined with its thick atmosphere) has led to it becoming the hottest planet in the Solar System. That, combined with its sulfuric acid rains makes Mars a much more attractive option.
Additionally, Mars is closer to Earth than the other Solar planets – except for Venus, but we already covered why it’s not a very good option! This would make the process of colonizing it easier. In fact, every few years when the Earth and Mars are at opposition – i.e. when they are closest to each other – the distance varies, making certain “launch windows” ideal for sending colonists.
For example, on April 8th, 2014, Earth and Mars were 92.4 million km (57.4 million miles) apart at opposition. On May 22nd, 2016, they will be 75.3 million km (46.8 million miles) apart, and by July 27th of 2018, a meager 57.6 million km (35.8 million miles) will separate our two worlds. During these windows, getting to Mars would be a matter of months rather than years.
Also, Mars has vast reserves of water in the form of ice. Most of this water ice is located in the polar regions, but surveys of Martian meteorites have suggested that much of it may also be locked away beneath the surface. This water could be extracted and purified for human consumption easily enough.
In his book, The Case for Mars, Robert Zubrin also explains how future human colonists might be able to live off the land when traveling to Mars, and eventually colonize it. Instead of bringing all their supplies from Earth – like the inhabitants of the International Space Station – future colonists would be able to make their own air, water, and even fuel by splitting Martian water into oxygen and hydrogen.
New estimates of water ice on Mars suggest there may be large reservoirs of underground ice at non-polar latitudes. Credit: Feldman et al., 2011
Preliminary experiments have shown that Mars soil could be baked into bricks to create protective structures, which would reduce the amount of material that needs to be shipped to the surface. Earth plants could eventually be grown in Martian soil too, assuming they get enough sunlight and carbon dioxide. Over time, planting on the native soil could also help to create a breathable atmosphere.
Challenges:
Despite the aforementioned benefits, there are also some rather monumental challenges to colonizing the Red Planet. For starters, there is the matter of the average surface temperature, which is anything but hospitable. While temperatures around the equator at midday can reach a balmy 20 °C, at the Curiosity site – the Gale Crater, which is close to the equator – typical nighttime temperatures are as low as -70 °C.
The gravity on Mars is also only about 40% of what we experience on Earth’s, which would make adjusting to it quite difficult. According to a NASA report, the effects of zero-gravity on the human body are quite profound, with a loss of up to 5% muscle mass a week and 1% of bone density a month.
Naturally, these losses would be lower on the surface of Mars, where there is at least some gravity. But permanent settlers would still have to contend with the problems of muscle degeneration and osteoporosis in the long run.
The Biosphere 2 project is an attempt to simulate Mars-like conditions on Earth. Credit: Science Photo Library
And then there’s the atmosphere, which is unbreathable. About 95% of the planet’s atmosphere is carbon dioxide, which means that in addition to producing breathable air for their habitats, settlers would also not be able to go outside without a pressure suit and bottled oxygen.
Mars also has no global magnetic field comparable to Earth’s geomagnetic field. Combined with a thin atmosphere, this means that a significant amount of ionizing radiation is able to reach the Martian surface.
Thanks to measurements taken by the Mars Odyssey spacecraft’s Mars Radiation Environment Experiment (MARIE), scientists learned that radiation levels in orbit above Mars are 2.5 times higher than at the International Space Station. Levels on the surface would be lower, but would still be higher than human beings are accustomed to.
In fact, a recent paper submitted by a group of MIT researchers – which analyzed the Mars One plan to colonize the planet beginning in 2020 – concluded that the first astronaut would suffocate after 68 days, while the others would die from a combination of starvation, dehydration, or incineration in an oxygen-rich atmosphere.
Artist’s concept of a Martian astronaut standing outside the Mars One habitat. Credit: Bryan Versteeg/Mars One
In short, the challenges to creating a permanent settlement on Mars are numerous, but not necessarily insurmountable. And if we do decide, as individuals and as a species, that Mars is to become a second home for humanity, we will no doubt find creative ways to address them all.
Who knows? Someday, perhaps even within our own lifetimes, there could be real Martians. And they would be us!
Universe Today has many interesting articles about the possibility of humans living on Mars. Here’s a great article by Nancy Atkinson about the possibility of a one-way, one-person trip to Mars
Eris is the largest dwarf planet in the Solar System, and the ninth largest body orbiting our Sun. Sometimes referred to as the “tenth planet”, it’s discovery is responsible for upsetting the traditional count of nine planets in our Solar System, as well as leading the way to the creation of a whole new astronomical category.
Located beyond the orbit of Pluto, this “dwarf planet” is both a trans-Neptunian object (TNO), which refers to any planetary object that orbits the Sun at a greater distance than Neptune – or 30 astronomical units (AU). Because of this distance, and the eccentricity of its orbit, it is also a member of a the population of objects (mostly comets) known as the “scattered disk”.
The discovery of Eris was so important because it was a celestial body larger than Pluto, which forced astronomers to consider, for the first time in history, what the definition of a planet truly is.
Discovery:
Eris, which has the full title of 136199 Eris, was first observed in 2003 during a Palomar Observatory survey of the outer solar system by a team led by Mike Brown, a professor of planetary astronomy at the California Institute of Technology. The discovery was confirmed in January 2005 after the team examined the pictures obtained from the survey in detail.
Classification:
At the time of it’s discovery, Brown and his colleagues believed that they had located the 10th planet of our solar system, since it was the first object in the Kuiper Belt found to be bigger than Pluto. Some astronomers agreed and liked the designation, but others objected since they claimed that Eris was not a true planet. At the time, the definition of “planet” was not a clear-cut since there had never been an official definition issued by the International Astronomical Union (IAU).
The matter was settled by the IAU in the summer of 2006. They defined a planet as an object that orbits the Sun, which is large enough to make itself roughly spherical. Additionally, it would have to be able to clear its neighborhood – meaning it has enough gravity to force any objects of similar size or that are not under its gravitational control out of its orbit.
In addition to finally defining what a planet is, the IAU also created a new category of “dwarf planets“. The only difference between a planet and a dwarf planet is that a dwarf planet has not cleared its neighborhood. Eris was assigned to this new category, and Pluto lost its status as a planet. Other celestial bodies, including Haumea, Ceres, and Makemake, have been classified as dwarf planets.
Artist’s impression shows the distant dwarf planet Eris, highlighting its bright surface. Credit: ESO
Naming:
Eris is named after the Greek goddess of strife and discord. The name was assigned on September 13th, 2006, following an unusually long consideration period that arose over the issue of classification. During this time, the object became known to the wider public as Xena, which was the name given to it by the discovery team.
The team had been saving this name, which was inspired by the title character of the television series Xena: Warrior Princess, for the first body they discovered that was larger than Pluto. They also chose it because it started with the letter X, a reference to Percival Lowell’s hunt for a planet he believed to exist the edge of the Solar System (which he referred to as “Planet X“).
According to fellow astronomer and science writer Govert Schilling, Brown initially wanted to call the object “Lila”. This name was inspired by a concept in Hindu mythology that described the cosmos as the outcome of a game played by Brahma, and also because it was similar to “Lilah” – the name of Brown’s newborn daughter.
Size and Orbit:
The actual size and mass of Eris has been the subject of debate, as official estimates have changed with time and subsequent viewing. In 2005, using images from the Hubble Space Telescope. the diameter of Eris was measured to be 2397 ± 100 km (1,489 miles). In 2007, a series of observations of the largest trans-Neptunian objects with the Spitzer Space Telescope estimated Eris’s diameter at 2600 (+400/-200) km (1616 miles).
A diagram showing solar system orbits. The highly tilted orbit of Eris is in red. Credit: NASA
The most recent observation took place in November of 2010, when Eris was the subject of one of the most distant stellar occultations yet achieved from Earth. The teams findings were announced on October 2011, and contradicted previous findings with an estimated diameter of 2326 ± 12 km (1445 miles).
Because of these differences, astronomers have been hard-pressed to maintain that Eris is more massive than Pluto. According to the latest estimates, the Solar System’s “ninth planet” has a diameter of 2368 km (1471 miles), placing it on par with Eris. Part of the difficulty in accurately assessing the planet’s size comes from interference from Pluto’s atmosphere. Astronomers expect a more accurate appraisal when the New Horizons space probe arrives at Pluto in July 2015.
Eris has an orbital period of 558 years. Its maximum possible distance from the Sun (aphelion) is 97.65 AU, and its closest (perihelion) is 37.91 AU. This means that Eris and its moon are currently the most distant known objects in the Solar System, apart from long-period comets and space probes.
Eris’s orbit is highly eccentric, and brings Eris to within 37.9 AU of the Sun, a typical perihelion for scattered objects. This is within the orbit of Pluto, but still safe from direct interaction with Neptune (29.8-30.4 AU). Unlike the eight planets, whose orbits all lie roughly in the same plane as the Earth’s, Eris’s orbit is highly inclined – the planet is tilted at an angle of about 44° to the ecliptic.
Moons:
Eris has one moon called Dysnomia, which is named after the daughter of Eris in Greek mythology, which was first observed on September 10th, 2005 – a few months after the discovery of Eris. The moon was spotted by a team using the Keck telescopes in Hawaii, who were busy carrying out observations of the four brightest TNOs (Pluto, Makemake, Haumea, and Eris) at the time.
Eris (center) and its moon of Dysnomia (left of center), taken by the Hubble Space Telescope. Credit: NASA/ESA/Mike Brown
Interesting Facts:
The dwarf planet is rather bright and can be detected using something as simple as a small telescope. Models of internal heating via radioactive decay suggest that Eris may be capable of sustaining an internal ocean of liquid water at the mantle-core boundary. These studies were conducted by Hauke Hussmann and colleagues from the Institute of Astronomy, Geophysics and AtmosphericSciences (IAG) at the University of SãoPaulo.
Brown and the discovery team followed up their initial identification of Eris with spectroscopic observations of the planet, which were made on January 25th, 2005. Infrared light from the object revealed the presence of methane ice, indicating that the surface may be similar to that of Pluto and of Neptune’s moon Triton.
Due to Eris’s distant eccentric orbit, its surface temperature is estimated to vary between about 30 and 56 K (?243.2 and ?217.2 °C). This places it on par with Pluto’s surface temperature, which ranges from 33 to 55 K (-240.15 and -218.15 °C).
We have many interesting articles on planets here at Universe Today, including this article on What is the newest planet and the 10th planet.
If you are looking for more information, try Eris and NASA’s Solar System Exploration entry.
Skylab, America’s First manned Space Station. Photo taken by departing Skylab 4 crew in Feb. 1974. Credit: NASA
Before there was the International Space Station, before there was Mir, there was Skylab. Established in 1973, and remaining in orbit until 1979, this orbital space station was American’s first long-duration orbital workshop, and the ancestor of all those that have followed.
Originally conceived of in 1969, the plans for the station were part of a general winding down that took place during the last years of the Space Race – which officially ran from 1955 to 1972. Having sent astronauts into orbit and achieved the dream of manned missions to the Moon, the purpose of Skylab was to achieve a lasting presence in space. Rather than simply “getting there first”, NASA was now concerned with staying there.
Planning:
The seeds of Skylab were planted as early as 1959, when Wernher von Braun – the head of the Development Operations Division at the Army Ballistic Missile Agency – proposed a mission that would use a multistage rocket to place men on the Moon. As part of this mission, the upper stage of the rocket would be deposited around the Earth to function as an orbital laboratory. Known as Horizon, these plans were eventually be seized upon by NASA, which was rapidly forming at the time.
A 1967 conceptual drawing of the Gemini B reentry capsule separating from the MOL at the end of a mission. Credit: NASA
Similarly, as of September 1963, the US Department of Defense (DoD) and NASA began collaborating on a manned facility known as the “Manned Orbital Laboratory” (MOL). The initial DoD plan called for a station that would be the same diameter as a Titan II upper stage, and which would primarily be intended for photo reconnaissance using large telescopes directed by a two-man crew.
As the head of the Marshall Space Flight Center during the 1960s, Von Braun became concerned that his employees would not have work beyond developing the Saturn rockets intended for the Apollo program. As a result, he began advocating for the creation of a space station using modified Apollo hardware – which included the S-II second stage of a Saturn V rocket.
Throughout 1965, several more proposals were considered that relied on the Saturn S-IVB stage to create a space station. As part of NASA’s The Orbital Workshop program, this proposal also called for sending a crew to man the station using a Apollo Command-Service Module (CSM) aboard a Saturn IB rocket.
This artist’s concept is a cutaway illustration of the Skylab with the Command/Service Module being docked to the Multiple Docking Adapter. Credit: NASA
The crew would dock with the station, vent the residual propellants from the S-IVB stage, fill the hydrogen tank with a breathable oxygen atmosphere, and then enter the tank and outfit it as a station. On August 8th, 1969, after years of development and workshops, the McDonnel Douglas Corporation received a contract to create an Orbital Workshop out of two existing S-IVB stages.
In February of 1970, the program was renamed “Skylab” as a result of a NASA contest. A Saturn V rocket that was originally produced for the Apollo program – before the cancellation of Apollo 18, 19, and 20 – was re-purposed and redesigned to carry the station into orbit.
Launch:
Skylab was launched on May 14th, 1973 on a mission that is sometimes referred to as Skylab 1 (or SL-1). Severe damage was sustained during the launch when the station’s meteoroid shield and one of the two solar panels tore off due to vibrations.
Since the station was designed to face the Sun in order to get as much power as possible, and the shield was ripped off, the station rose to a temperature of 52°C. As a result, scientists had to move the space station and effect repairs before astronauts could be dispatched to it.
Launch of the modified Saturn V rocket carrying the Skylab space station. Credit: NASA
Missions:
The first manned mission (designated Skylab 2, or SL-2) took place on May 25th, 1973, atop a Saturn IB and involved extensive repairs to the station. This mission last four weeks, and astronauts Charles Conrad, Jr., Paul J. Weitz, Joseph P. Kerwin were the crew members. During the mission, the crew conducted a number of experiments, including solar astronomy and medical studies, and three EVAs (extra-vehicular activities) were completed as well.
The second manned mission, also known as Skylab 3 (SL-3), was launched on July 28th, 1973. The crew consisted of Alan L. Bean, Jack R. Lousma, and Owen K. Garriott. The mission lasted 59 days and 11 hours, during which time the crew carried out additional repairs as well as performing scientific and medical experiments.
The third and final mission to the Skylab (Skylab 4, SL-4) was the longest, lasting 84 days and one hour. Gerald P. Carr, William R. Pogue, Edward G. Gibson were the crew, and in addition to performing various experiments, they also observed the Comet Kohoutek. The crew conducted three EVAs which lasted a total of 22 hours and 13 minutes.
Skylab in February 1974, pictured by the SL-4 crew as they depart the station to return to Earth. Credit: NASA
Skylab was occupied a total of 171 days and orbited the Earth more than 2,476 times during the course of its service. Each Skylab mission set a record for the amount of time astronauts spent in space.
Decommissioning:
Though NASA hoped that the station would remain in orbit for ten years, by 1977, it became clear that it would not be able to maintain a stable orbit for that long. As a result, after SL-4, preparations were made to shut down all operations and de-orbit the station.
Skylab’s demise was an international media event, with merchandising of T-shirts and hats with bullseyes, wagering on the time and place of re-entry, and nightly news reports. In the hours before re-entry, ground controllers adjusted Skylab’s orientation to try to minimize the risk of re-entry on a populated area.
They aimed the station at a spot 1,300 km (810 miles) south southeast of Cape Town, South Africa, and re-entry began at approximately 16:37 UTC, July 11, 1979. The debris reached Earth on July 11th, 1979, raining down over the Indian Ocean and parts of Australia.
On May 13, NASA commemorated the 40th anniversary of Skylab’s liftoff with a special roundtable discussion broadcast live on NASA TV. The event took place at NASA’s Headquarters in Washington, DC, and participants included Skylab and current ISS astronauts and NASA human spaceflight managers.
While the station did not have the history of service that NASA initially hoped for, the development, deployment and crewed missions to Skylab were essential to the creation of the International Space Station, which began almost 20 years after Skylab came home.
We have many interesting articles on the Apollo program and space stations here at Universe Today. For example, here are some articles on Apollo 20 and the International Space Station.
Alert: mild spoilers lie ahead, as we’ll be discussing minor plot points of the book The Martian. What, you haven’t read it yet? Have you been stranded on Mars? Don’t make us pull your geek card…
Never mind The Avengers or the seventh installment of the Star Wars franchise… some early stills from the big screen adaptation of Andy Weir’s The Martian have been circulating around ye ole web as of late, and we like what we see.
Mars population: 1. Image credit: 20th Century Fox/Empire
Self-published in 2012 and lauded for its scientific accuracy, The Martian follows the exploits of astronaut Marc Watney (played by Matt Damon in the upcoming film) as he struggles to stay alive on Mars. Watney must rally every bit of scientific expertise at his command to accomplish everything from growing food to establishing communications to surviving the disco music and bad 70s TV left behind by fellow crew members.
The 20 Century Fox film adaptation is directed by Ridley Scott (of Alien and Blackhawk Down fame) and promises to have a ‘successful failure’ vibe in the tradition of Ron Howard’s Apollo 13. Heck, reading The Martian, we simply love how it breaks the convention advocated at innumerable writing workshops that exposition is somehow always bad. Engineering and science geeks want to peek under the hood, and see what makes that warp drive tick. The Martian breaks very few rules when it comes to getting the science right, and there’s high hopes that this will translate well on the big screen.
Stranded on the Red Planet… Image credit: 20th Century Fox/Empire
From the design of Watney’s Mars excursion suit to the expedition rover he uses to cross the Martian terrain, we’re seeing lots of actual NASA designs being incorporated into the production.
“NASA was very involved in consulting for the film,” author Andy Weir told Universe Today. “The production got numerous people in both NASA and JPL involved and listened very closely to what they had to say.”
One of our favorite bits from the book is where Watney must use the rising and setting of the twin Martian moons Phobos and Deimos for a rough dead reckoning while travelling over the open Martian terrain. It’s a terrific scene with some possibilities for some great panoramic vistas, and we hope it survives into the film adaptation.
We also hope that the first NASA rover to roll across the soils of Mars (hint: it wasn’t Curiosity, Spirit or Opportunity) makes an appearance in the movie, as it did in the book.
Matt Damon on the set of The Martian. Image credit: 20th Century Fox/Empire
The current release date set by 20th Century Fox is November 27, 2015 and Mr. Weir noted that we may be seeing the very first trailers for The Martian very soon, possibly in the June time frame.
And did you know? The cover for the script for The Martian—complete with early conceptual sketches by director Ridley Scott—actually flew aboard last year’s EFT-1 mission to test the Orion capsule in space.
The cover of the draft of the script for The Martian that flew on EFT-1. Click here for the full image (warning for rough language) Image credit: 20th Century Fox
Unlike trendy dystopian futures that are all the rage these days, The Martian depicts an optimistic future, a time where budgetary woes have been overcome and humans are living and working on Mars. This may well have been the true reason that the novel resonated so well throughout the science and space community: it conveys a message of a future that we all hope will be a reality in our lifetimes.
We even see a direct sci-fi lineage between The Martian and the classic 1954 science fiction tale The Cold Equationsby Tom Godwin. The universe is indeed out to kill us, and only science can save the day.
The cast of The Martian. Image credit: 20th Century Fox/People
It’ll be interesting to see if The Martian becomes the breakout hit of 2015. Also starring Michael Pena, Mackenzie David, Sean Bean, Donald Glover, Kate Mara, Sebastian Stan, Jeff Daniels, Chiwetel Ejiofor, and Jessica Chastain, The Martian features an all-star cast. We’re also curious to know if the film will have a disco soundtrack, but the author isn’t telling.
Much of the Mars-scapes for The Martian are being filmed in the deserts of Wadi Rum in southern Jordan. We traversed this region during our global backpacking trek in early 2007 and can attest that it is suitably Martian in appearance, though of course, we’ve yet to journey to the Red Planet… Weir’s book and the upcoming film will have to suffice for now.
A NASA spokesperson played by Kristin Wiig. Image credit: 20th Century Fox/People
Wadi Rum also simulated Mars in the films Red Planet and The Last Days on Mars.
We’ll definitely be waiting in line come opening day!
Check out this exclusive interview with The Martian author Andy Weir in the recent Weekly Spacehangout:
When you’re walking around on soft ground, do you notice how your feet leave impressions? Perhaps you’ve tracked some of the looser earth in your yard into the house on occasion? If you were to pick up some of these traces – what we refer to as dirt or soil – and examine them beneath a microscope, what would you see?
Essentially, you would be seeing the components of what is known as regolith, which is a collection of particles of dust, soil, broken rock, and other materials found here on Earth. But interestingly enough, this same basic material can be found in other terrestrial environments as well – including the Moon, Mars, other planets, and even asteroids.
Definition:
The term regolith refers to any layer of material covering solid rock, which can come in the form of dust, soil or broken rock. The word is derived from the combination of two Greek words – rhegos (which means “blanket”) and lithos (which means “rock).
Earth:
On Earth, regolith takes the form of dirt, soil, sand, and other components that are formed as a result of natural weathering and biological processes. Due to a combination of erosion, alluvial deposits (i.e. moving water deposing sand), volcanic eruptions, or tectonic activity, the material is slowly ground down and laid out over solid bedrock.
Picture of Mt Magnet in the Central Yilgarn Craton in Western Australia, which dates to the Precambrian Era. Credit: geomorphologie.revues.org
It can be made up of clays, silicates, various minerals, groundwater, and organic molecules. Regolith on Earth can vary from being essentially absent to being hundreds of meters thick. Its can also be very young (in the form of ash, alluvium, or lava rock that was just deposited) to hundreds of millions of years old (regolith dating to the Precambrian age occurs in parts of Australia).
On Earth, the presence of regolith is one of the important factors for most life, since few plants can grow on or within solid rock and animals would be unable to burrow or build shelter without loose material. Regolith is also important for human beings since it has been used since the dawn of civilization (in the form of mud bricks, concrete and ceramics) to build houses, roads, and other civil works.
The difference in terminology between “soil” (aka. dirt, mud, etc.) and “sand” is the presence of organic materials. In the former, it exists in abundance, and is what separates regolith on Earth from most other terrestrial environments in our Solar System.
The Moon:
The surface of the Moon is covered with a fine powdery material that scientists refer to it as “lunar regolith”. Nearly the entire lunar surface is covered with regolith, and bedrock is only visible on the walls of very steep craters.
Earth viewed from the Moon by the Apollo 11 spacecraft, across a sea of lunar soil. Credit: NASA
The Moon regolith was formed over billions of years by constant meteorite impacts on the surface of the Moon. Scientists estimate that the lunar regolith extends down 4-5 meters in some places, and even as deep as 15 meters in the older highland areas.
When the plans were put together for the Apollo missions, some scientists were concerned that the lunar regolith would be too light and powdery to support the weight of the lunar lander. Instead of landing on the surface, they were worried that the lander would just sink down into it like a snowbank.
However, landings performed by robotic Surveyor spacecraft showed that the lunar soil was firm enough to support a spacecraft, and astronauts later explained that the surface of the Moon felt very firm beneath their feet. During the Apollo landings, the astronauts often found it necessary to use a hammer to drive a core sampling tool into it.
Once astronauts reached the surface, they reported that the fine moon dust stuck to their spacesuits and then dusted the inside of the lunar lander. The astronauts also claimed that it got into their eyes, making them red; and worse, even got into their lungs, giving them coughs. Lunar dust is very abrasive, and has been noted for its ability to wear down spacesuits and electronics.
Alan Bean takes a sample of lunar regolith during the Apollo 12 mission. Credit: NASA
The reason for this is because lunar regolith is sharp and jagged. This is due to the fact that the Moon has no atmosphere or flowing water on it, and hence no natural weathering process. When the micro-meteoroids slammed into the surface and created all the particles, there was no process for wearing down its sharp edges.
The term lunar soil is often used interchangeably with “lunar regolith”, but some have argued that the term “soil” is not correct because it is defined as having organic content. However, standard usage among lunar scientists tends to ignore that distinction. “Lunar dust” is also used, but mainly to refer to even finer materials than lunar soil.
As NASA is working on plans to send humans back to the Moon in the coming years, researchers are working to learn the best ways to work with the lunar regolith. Future colonists could mine minerals, water, and even oxygen out of the lunar soil, and use it to manufacture bases with as well.
Mars:
Landers and rovers that have been sent to Mars by NASA, the Russians and the ESA have returned many interesting photographs, showing a landscape that is covered with vast expanses of sand and dust, as well as rocks and boulders.
A successful scoop of Martian regolith performed by NASA’s Phoenix lander. Credit: NASA/JPL-Caltech/University of Arizona/Max Planck Institute
Compared to lunar regolith, Mars dust is very fine and enough remains suspended in the atmosphere to give the sky a reddish hue. The dust is occasionally picked up in vast planet-wide dust storms, which are quite slow due to the very low density of the atmosphere.
The reason why Martian regolith is so much finer than that found on the Moon is attributed to the flowing water and river valleys that once covered its surface. Mars researchers are currently studying whether or not martian regolith is still being shaped in the present epoch as well.
It is believed that large quantities of water and carbon dioxide ices remain frozen within the regolith, which would be of use if and when manned missions (and even colonization efforts) take place in the coming decades.
Mars moon of Deimos is also covered by a layer of regolith that is estimated to be 50 meters (160 feet) thick. Images provided by the Viking 2 orbiter confirmed its presence from a height of 30 km (19 miles) above the moon’s surface.
Asteroids and Outer Solar System:
The only other planet in our Solar System that is known to have regolith is Titan, Saturn’s largest moon. The surface is known for its extensive fields of dunes, though the precise origin of them are not known. Some scientists have suggested that they may be small fragments of water ice eroded by Titan’s liquid methane, or possibly particulate organic matter that formed in Titan’s atmosphere and rained down on the surface.
Another possibility is that a series of powerful wind reversals, which occur twice during a single Saturn year (30 Earth years), are responsible for forming these dunes, which measure several hundred meters high and stretch across hundreds of kilometers. Currently, Earth scientists are still not certain what Titan’s regolith is composed of.
Data returned by the Huygens Probe’s penetrometer indicated that the surface may be clay-like, but long-term analysis of the data has suggested that it may be composed of sand-like ice grains. The images taken by the probe upon landing on the moon’s surface show a flat plain covered in rounded pebbles, which may be made of water ice, and suggest the action of moving fluids on them.
Asteroids have been observed to have regolith on their surfaces as well. These are the result of meteoriod impacts that have taken place over the course of millions of years, pulverizing their surfaces and creating dust and tiny particles that are carried within the craters.
False color picture taken by NASA’s NEAR Shoemaker camera of Eros’ 5.3-kilometer (3.3-mile) surface crater, showing the presence of regolith inside. Credit: NASA/JPL/JHUAPL
NASA’s NEAR Shoemaker spacecraft produced evidence of regolith on the surface of the asteroid 433 Eros, which remains the best images of asteroid regolith to date. Additional evidence has been provided by JAXA’s Hayabusa mission, which returned clear images of regolith on an asteroid that was thought to be too small to hold onto it.
Images provided by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras on board the Rosetta Spacecraft confirmed that the asteroid 21 Lutetia has a layer of regolith near its north pole, which was seen to flow in major landslides associated with variations in the asteriod’s albedo.
To break it down succinctly, wherever there is rock, there is likely to be regolith. Whether it is the product of wind or flowing water, or the presence of meteors impacting the surface, good old fashioned “dirt” can be found just about anywhere in our Solar System; and most likely, in the universe beyond…
We’ve done several articles about the Moon’s regolith here on Universe Today. Here’s a way astronauts might be able to extract water from lunar regolith with simple kitchen appliances, and an article about NASA’s search for a lunar digger.
Want to buy some lunar regolith simulant? Here’s a site that lets you buy it. Do you want to be a Moon miner? There’s lots of good metal in that lunar regolith.
These images show Pluto in the latest series of New Horizons Long Range Reconnaissance Imager (LORRI) photos, taken May 8-12, 2015. Hints of possible complex surface geology and the polar cap first seen in April are visible. Credit: NASA
Hey Pluto, it’s great to see your face! Since sending its last batch of images in April, NASA’s New Horizons probe lopped off another 20 million miles in its journey to the mysterious world. Among the latest revelations: the dwarf planet displays a much more varied surface and the bright polar cap discovered earlier this spring appears even bigger.
Comparison of the April image of one hemisphere of Pluto with the same hemisphere photographed in May. The photos have been rotated to align Pluto’s rotational axis with the vertical direction (up-down), as shown schematically in the center panel. Between April and May, Pluto grew larger as the spacecraft got closer, with Pluto’s apparent size increasing by approximately 50%. Pluto rotates around its axis every 6.4 Earth days; this and the images below show the variations in Pluto’s surface features during its rotation. Credit: NASA
“These new images show us that Pluto’s differing faces are each distinct; likely hinting at what may be very complex surface geology or variations in surface composition from place to place,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado.
Compare Pluto’s polar cap (white spot at top of the globe), first seen in April (left) with the latest image taken on May 10. Approximately the same face of Pluto is shown in both images. The cap’s extent varies with longitude. Credit: NASA
Mission scientists caution against over-interpreting some of the smaller details. The photos have been processed using a method called deconvolution, which strips away the out-of-focus information to enhance features on Pluto. Deconvolution can occasionally add “false” details or artifacts, so the smallest features in these pictures will need to be confirmed by images taken from closer range in the next few weeks.
Pluto compared on April 16, 2015 and May 12. Credit: NASA
Compared to recent photos of Ceres, the other dwarf planet in the limelight this season, Pluto shows only light and dark blotches. That’s how Ceres started out too. All those variations in tone and texture suggest a fascinating and complex surface. And it’s clear that the polar cap — whatever it might ultimately be — is extensive and multi-textured. The images were taken from a little less than 50 million miles (77 million km) away or about the same distance Mars is from Earth during a typical opposition.
New Horizons current position and particulars on May 28, 2015. Credit: NASA
Watch for dramatic improvements in the images as New Horizons speeds toward its target, covering 750,000 miles per day until closest approach on July 14. By late June, they’ll have four times the resolution; during the flyby that will improve to 5,000 times. The spacecraft is currently 2.95 billion miles from Earth. Light, traveling at 186,00o miles per second, requires 8 hours and 47 minutes – the length of a typical work day – to make the long round trip.
The summer season means long days and short nights, as observers in the northern hemisphere must stay up later each evening waiting for darkness to fall. It also means that the best season to spot that orbital outpost of humanity—the International Space Station—is almost upon us. Get set for multiple passes a night for observers based in mid- to high- northern latitudes, starting this week.
This phenomenon is the result of the station’s steep 52 degree inclination orbit. This means that near either solstice, the ISS spends a span of several days in permanent illumination. Multiple sightings favor the southern hemisphere around the December solstice and the northern hemisphere right around the upcoming June solstice.
Here’s a rundown of the ‘ISS all night’ season for 2015. The Sun rises on the ISS after a brief three minute orbital night on May 30th, 2015 at 16:43 UT, and doesn’t set again until five days later on June 4th at 4:57 UT over the central US. The ISS full illumination season comes a bit early this year—a few weeks before the June 21st northward solstice—and the next prospect at the end of July sees the Sun angle juuust shy of actually creating a second summer season.
The orbital trace of the ISS starting on May 30th. Image credit: Orbitron
NASA engineers refer to this period as high solar beta angle season. For a satellite in low Earth orbit, the beta angle describes the angle between its orbital plane and the relative direction of the Sun. Beta angle governs the satellite’s length of time in darkness and daylight. In the shuttle era, the Space Shuttle could not approach the ISS during these ‘beta cutout’ times, and the station generally goes into ‘rotisserie mode,’ as the ISS is rotated and its solar panels feathered to create alternating regions of artificial darkness in an effort to combat the continuous heating.
A depiction of the beta-angle of a satellite. Image credit: Fomirax/Wikimedia Commons
Why the 52 degree inclination orbit for the station? This allows the ISS to be accessible from launch sites worldwide in the spirit of international cooperation exemplified by the ISS. The station can and has been reached by cargo and human crews launching from Cape Canaveral and the Kennedy Space Center in Florida, the Baikonur Cosmodrome, the Tanegashima space port in Japan, and Kourou space center in French Guiana.
Our friend @OzoneVibe on Twitter suggested to us a few years back that a one night marathon session of ISS sightings be known as a FISSION, which stands for Four/Five ISS sightings In One Night. The prospective latitudes to carry out this feat run from 45 to 55 degrees north, which corresponds with northern Europe, the United Kingdom, and the region just north and south of the U.S./Canadian border.
An amazing sequence showing a complete ISS pass overhead. Image credit and copyright: Alan Dyer/Amazing Sky Photography
At 72.8 by 108.5 metres in size and orbiting the Earth once every 92 minutes at an average 400 kilometres in altitude, the ISS is the brightest object in low Earth orbit, and reaches magnitude -2 in brightness—not quite as bright as Venus at maximum brightness—on a good overhead pass. Depending on the approach angle, I can just make out a bit of detail when the ISS is near the zenith, looking like either a box, a close double star, or a tiny Star Wars TIE fighter through binoculars. Numerous apps and platforms exist to predict ISS passes based on location, though our favorite is still the venerable Heavens-Above. It’s strange to think, we were using Heavens-Above to chase Mir back in the late 1990s!
There’s another interesting challenge, which, to our knowledge, has never been captured as we near high beta angle season for the ISS: catching an ‘ISS wink out,’ or that brief sunset followed by sunrise a few minutes later on the same pass. It’s worth noting that the central United States may see just such an event during an early morning pass on June 4th… will you be the first to witness it?
An ISS pass over Denmark, Maine. Image credit: David Dickinson
Photographing the ISS is as easy as setting a DSLR on a tripod with a wide field of view lens, and doing a simple time exposure as it drifts by. Be sure to manually set the focus before the pass… Venus is currently well placed as a ‘mock ISS’ to get a fix on beforehand.
And amateur observers can even capture detail on the ISS, though this requires a camera running video coupled to a telescope. High precession tracking is desirable, though not mandatory: we’ve actually got descent results manually aiming a scope at the ISS with video running. The ISS appears in post production, occasionally skipping through the field of view.
Another unique method is to know when the ISS will transit the Sun, Moon or near a bright planet or star, aim your rig at the right spot, and let the station come to you. A good site to tailor alerts for such occurrences is CALSky.
The ISS transits the Sun in 2012. Image credit and copyright: Fred Locklear
After high beta angle season, missions to and from the ISS will resume. This includes the return of ISS crewmembers Shkaplerov, Christoforetti and Virts on June 7th, followed by a Soyuz launch with Kononeko, Yui, and Lindgren on July 24th. Also on tap is SpaceX’s Dragon capsule on CRS-7 launching on June 26th, the return to flight for Progress on July 3rd, and a HTV-5 launch for JAXA on August 17th. These can also provide interesting views for ground observers as well, as these spacecraft follow the ISS in its orbit on approach like tiny fainter ‘stars.’
A busy season indeed. Don’t miss a chance to see the ISS coming to a sky near you, and watch as humans work together aboard this orbiting science platform in space.
